This invention relates to an image sensing apparatus comprising a portable information device and an image sensing cartridge connected thereto.
Recent reductions in the size of portable personal computers, the combination of such portable personal computers with a communication function and improvements in the capabilities of electronic notebooks have made possible the use of portable, compact information devices of the kind illustrated in FIG. 1. At the same time, arranging it so that image information can be handled is deemed to be the most important factor as far as such portable information devices is concerned.
Various methods have been proposed for incorporating an image sensing function in such a portable information device to allow the sensing and entry of characters, images and the like so that the device may be provided with a function equivalent to that of a facsimile machine or camera. However, it is difficult to imagine that all portable information devices will require the above-described image sensing unit. In addition, if one portable information device is provided with only one identical image sensing unit, it will be very difficult for the device to accommodate the trend toward multiple functions in which the device can be used as both a camera and as a facsimile machine.
Accordingly, consideration has been given to using a card-type image sensing cartridge, of the kind shown in FIGS. 2 and 3, that is coupled to the portable information device via a card interface. In this case, image sensing cartridges may be interchanged so that an image sensing apparatus comprising the portable information device and the image sensing cartridge can be used in a variety of applications.
FIG. 1 is a perspective view of a portable information device, FIG. 2 a perspective view of an image sensing cartridge, FIG. 3 a view showing the internal construction of the cartridge, FIG. 4 a perspective view showing the portable information device and the image sensing cartridge after they are docked, and FIG. 5 an electrical block diagram of the image sensing cartridge.
As shown in FIG. 1, numeral 8 denotes the portable information device, 9 an antenna for wireless communication, 10 an insertion port for inserting an image sensing cartridge, and 17 a display unit for displaying various information. In FIG. 2, numeral 62 denotes an image sensing cartridge having an opening 2 that allows entry of reflected light from a subject. In FIG. 3, numeral 3 denotes an optical system such an image pick-up lens or the like, 4 an image sensing element, 5 a substrate on which a drive IC or the like for driving the image sensing element 4 is mounted, 6 a DC-DC converter for generating the voltage needed to drive the image sensing element 4, and 7 a substrate on which a signal processing circuit for obtaining a prescribed signal from the output of the image sensing element 4 is mounted.
Shown in FIG. 5 are the image sensing element 4, such as a CCD, a preprocessor 33 for subjecting the output of the image sensing element 4 to CDS processing or the like, an A/D converter 34, a compressing processor 35 for reducing redundancy of digital image signal information, a memory 36, interface processing circuits (I/F) 37 and 42, a clock circuit 38 for generating a timing signal that drives the image sensing element 4, a drive circuit 39 for amplifying the timing signal so as to enable driving of the image sensing element 4, a DC-DC converter 40 for generating enough voltage from a prescribed voltage value to drive the image sensing element 4, and a central processing unit (CPU) 41 for controlling the ICs of the A/D converter 34, the memory 36 and the clock circuit 38, etc., as well as the optical system 3. Numeral 43 denotes a connector for interconnecting the image sensing cartridge 62 and the portable information device 8.
In the above-described arrangement, an image sensing command is transmitted from the portable information device 8 via the connector 43, whereupon the command enters the CPU 41 through the I/F 42. In response to this command, the CPU 41 introduces electric power to each of the signal processors and commands the clock 38 to output the timing signal for the image sensing element.
The timing signal outputted by the clock circuit 38 is converted into a signal, which is capable of driving the image sensing element 4, in the drive circuit 39 by the output obtained from the voltage conversion performed by the DC-DC converter 40. By virtue of the drive signal thus obtained, the image of the subject exposed by the image sensing element 4 is converted into an electrical signal, which is then sent to the preprocessor 33. The latter executes processing such as CDS processing and non-linearizing processing, which must be carried out before the output of the image sensing element 4 is subjected to an A/D conversion.
The output of the preprocessor 33 enters the A/D converter 34, where it is converted into a digital signal. The digital signal is then subjected to information compression, which is suited to the image sensing element 4, by the compressing processor 35. The compressed signal is held temporarily in the memory 36 before being sent to the recording medium of the portable information device via the I/F 37 and connector 43. The signal is thus recorded on the recording medium.
The image information sensed by the image sensing cartridge 62 and recorded in the portable information device 8 by the above-described processing is reproduced or edited in the portable information device 8 or used in communication.
In order to realize the image sensing cartridge 62 described above, it is necessary that the opening 2 of the image sensing cartridge 62 be situated inside the insertion port 10 of the portable information device 8, as shown in FIG. 4. This means that the aperture (a in FIG. 2) of the opening 2 must be made smaller than the length (b in FIG. 1) of the short side of the cross section possessed by the insertion port 10. Consequently, as evident from FIG. 3, it is required that the optical system 3 and image sensing element 4 within the image sensing cartridge 62 have fairly small apertures.
However, in a case where the aperture of the optical system 3 is made very small, problems are encountered in terms of lens capability (especially in terms of a decline in resolution and an increase in loss of absolute light quantity). Manufacture also becomes more complicated. Furthermore, it is difficult to assure brightness in a multiple focal-point lens such as a zoom lens. In addition, in order to obtain an ultra-small image sensing element 4, there is an increase in pixel density and an attendant decline in sensitivity.